1. Field of the Invention
The present invention relates to the use of protective pads to avoid injury to the median and ulnar nerves in the hand.
2. Information Disclosure Statement
Irritation and injury to the median (carpal tunnel syndrome) and ulnar (Guyon's canal syndrome) nerves in the hand is a common problem. The nerves pass through separate fibro-osseous canals within the wrist/palm. Nerve injury may occur as a result of compression, vibration, and traction. Common causes of nerve compression include use of a computer keyboard and mouse (mouse use places pressure primarily on the ulnar nerve), and holding a bicycle handlebar. Vibration induced nerve injury may occur from using gardening equipment (i.e., power lawn mowers, gasoline powered blowers, power string trimmers), operating heavy equipment (i.e., back hoes, road graders, tractors), and sports utilizing racquets or bats. Traction related nerve irritation might arise from frequent repetitive tasks involving hand/wrist motion such as occurs with assembly line work. Many activities may produce nerve irritation or injury through a combination of mechanisms such as compression and vibration. Examples of such activities include factory work involving the use of hand held power tools, driving/racing cars or boats, and piloting aircraft.
Nerve irritation in the hand may present with symptoms of tingling/numbness, pain, and weakness. The anatomical distribution of symptoms is dependent upon the location of nerve injury. Injury to the median nerve in the wrist/palm (i.e., carpal tunnel syndrome) typically involves sensory disturbances involving the thumb, index, long, and radial half ring fingers. Sensory disturbances associated with ulnar nerve injury in the wrist/palm (i.e., Guyon's canal syndrome) typically involve the small and ulnar half ring fingers. Motor involvement can include atrophy of the thenar muscles (i.e., median nerve injury) or hypothenar muscles (i.e., ulnar nerve) resulting in grip and pinch weakness. Pain is usually worse with activity. Night symptoms are a frequent complaint.
Treatment for median and ulnar nerve injury at the wrist/palm includes nonsteroidal anti-inflammatory medications (i.e., NSAIDs), cock-up wrist splints, activity modification, and local steroid injections into the nerve canals. Surgical decompression of the canals can be performed in those cases that do not improve with nonsurgical therapy.
Standard treatment for injury/irritation of the median and ulnar nerves at the wrist/palm includes the use of a cock-up wrist splint. These splints consist of a fabric or an elastic material body into which the hand and wrist are placed. A metal strip is incorporated into the volar aspect of the material body serving to maintain the wrist in a neutral position where nerve canal pressure is minimized. The body of the splint is generally secured with Velcro® straps allowing some degree of fit adjustment. This type of splint avoids excessive wrist dorsiflexion or palmarflexion, positions that increase nerve canal pressure and, hence, nerve irritation. Cock-up wrist splints also prevent repetitive wrist movements that can also cause nerve irritation. However, these splints do not address direct external nerve compression. In fact, the volar metal support overlies the nerves and may potentially transfer pressure to them.
Brinnand et al (U.S. Pat. No. 5,404,591 issued Apr. 11, 1995) designed a glove with padding around the wrist/carpal area to protect the skin and bones in this area. The glove was designed for users of electronic input devices such as a computer mouse or stylus. The padding was located across the entire wrist and palm without any recess to off load the median or ulnar nerves.
Dray (U.S. Pat. No. 5,921,949 issued Jul. 13, 1999) sought to protect the median nerve by designing a circumferential compression strap applied around the wrist. Compression by the strap was supposed to relax the flexor retinaculum and reverse anterior to posterior prolapse of the carpal tunnel thereby reducing stress on the median nerve. This orthosis did not address direct external pressure to the median and ulnar nerves. It also did not address traction stress to the median and ulnar nerves caused by repetitive wrist motion.
Gloves with pads have been produced to prevent vibration related nerve injury. Gloves have also been made incorporating air bladders to prevent transfer to vibration to the hand (U.S. Pat. No. 5,771,490 issued Jun. 30, 1998 to Reynolds, et al and U.S. Pat. No. 5,537,688 issued Jul. 23, 1996 to Reynolds, et al).
A variety of gloves have been developed for use in sports (U.S. Pat. No. 4,691,387 issued to Lopez on Sep. 8, 1987) such as racquetball, golf (U.S. Pat. No. 5,634,214 issued to St. Ville on Jun. 3, 1997), and baseball. These gloves are typically designed to improve a player's grip on the handle of the racquet or bat. Some of these gloves include padding in various areas. But, they do not specifically address nerve protection through impact or pressure avoidance to the nerves.
Standard bicycling gloves generally include a broad pad or combination of multiple pads to cushion the entire palm including the course of the median and ulnar nerves. Pads in standard bicycling gloves do not avoid pressure to the nerves since they lie directly over the nerves. There are at least three bicycling gloves that specifically address nerve irritation related to gripping a bicycle handlebar. The first such glove was designed by Minkow, et al (U.S. Pat. No. 6,289,517 issued Sep. 18, 2001) and it addresses protection of the median and ulnar nerves by placing padding of increased thickness directly over the nerves. The purpose of the padding is to cushion the nerves. The design of this glove does not attempt to relieve pressure from the nerves.
The second bicycling glove designed for nerve protection is the Louis Girneau Ergo Air glove (World patent pending). Information in its advertisement and packaging material states that it has “vents to prevent fatigue of the ulnar and median nerves.” The advertisement states “the unique ventilation system on the inside of the palm reduces numbness by increasing moisture diffusion and reducing heat.” Ventilation is afforded by stretch knit material in the palm. Other claims in the advertisement indicate “padding strategically placed to dampen vibration” and “padding eliminates pressure on the ulnar nerve.” Inspection of the product drawing depicted in the advertisement and analysis of the actual glove indicates that there is a U-shaped pad attached to the palm of the glove. The portions of the pad that comprise the longitudinal limbs of the U pass directly over the median and ulnar nerves. Hence, the pads cushion the median and ulnar nerves. But, the pads do not relieve pressure from the nerves by virtue of their location over the nerves.
The Grandoe Shock Tek (Trademark registration date Jan. 6, 1998 issued to Spitzer) is the third glove designed with nerve protection in mind. This glove utilizes prior art described in U.S. Pat. No. 6,006,751 issued Dec. 28, 1999 to Spitzer. The design of this glove specifically addresses pressure relief of the median nerve by using pads (Spitzer described using interrupted resilient protection to impart greater flexibility) placed parallel to the median nerve. There is a recess between the pads located over the median nerve. The Shock Tek glove does not address pressure relief for the ulnar nerve. In fact, the ulnar pad lies over the ulnar nerve.
There have been some inventions created to protect the median nerve by avoiding pressure to the nerve. These inventions have not addressed protection of the ulnar nerve with the exception of one by Spitzer (U.S. Pat. No. 6,006,751) in which he describes one embodiment of his invention that is a glove assembly that has a secondary notch situated over the ulnar nerve to prevent compression to the ulnar nerve. Spitzer's diagram of the secondary notch shows it to be a focal, concave cutout in the ulnar base of the resilient protector that is located ulnar to the median nerve. Therefore, only the proximal portion of the ulnar nerve is off-loaded as it courses through the proximal palm.
Eberbach (U.S. Pat. No. 5,810,753 issued Sep. 22, 1998) designed a wrist brace with parallel load-bearing members separated by a space over the median nerve. These load-bearing members extended from the distal forearm to the palm. The description of the size and location of the ulnar load-bearing member potentially placed it over the ulnar nerve.
Zamani (U.S. Pat. No. 6,200,286 B1 issued Mar. 13, 2001) described a wrist splint that was essentially a modification of a standard cock-up wrist splint. Instead of a flat volar rigid support typical of the standard splint, Zamani used a rigid preformed member with raised contact portions located on the sides of the carpal tunnel to avoid pressure to the median nerve. The brace did not include any mechanism for off-loading the ulnar nerve.
Nothing in the known prior art, either singly or in combination, discloses or suggests the present invention.